80-Bus News

  

September-October 1983, Volume 2, Issue 5











Page 32 of 67











Dis-assembly of NASCOM ROM BASIC Ver 4.7                PAGE    25

E69B F5         OUTC:   PUSH    AF              ; Save character
E69C 3A4510             LD      A,(CTLOFG)      ; Get control "O" flag
E69F B7                 OR      A               ; Is it set?
E6A0 C245F2             JP      NZ,POPAF        ; Yes - don't output
E6A3 F1                 POP     AF              ; Restore character
E6A4 C5                 PUSH    BC              ; Save buffer length
E6A5 F5                 PUSH    AF              ; Save character
E6A6 FE20               CP      " "             ; Is it a control code?
E6A8 DABFE6             JP      C,DINPOS        ; Yes - Don't INC POS(X)
E6AB 3A4210             LD      A,(LWIDTH)      ; Get line width
E6AE 47                 LD      B,A             ; To B
E6AF 3AAB10             LD      A,(CURPOS)      ; Get cursor position
E6B2 04                 INC     B               ; Width 255?
E6B3 CABBE6             JP      Z,INCLEN        ; Yes - No width limit
E6B6 05                 DEC     B               ; Restore width
E6B7 B8                 CP      B               ; At end of line?
E6B8 CC81EB             CALL    Z,PRNTCR        ; Yes - output CRLF
E6BB 3C         INCLEN: INC     A               ; Move on one character
E6BC 32AB10             LD      (CURPOS),A      ; Save new position
E6BF F1         DINPOS: POP     AF              ; Restore character
E6C0 C1                 POP     BC              ; Restore buffer length
E6C1 F5                 PUSH    AF              ; << This sequence >>
E6C2 F1                 POP     AF              ; << is not needed >>
E6C3 F5                 PUSH    AF              ; Save character
E6C4 C5                 PUSH    BC              ; Save buffer length
E6C5 4F                 LD      C,A             ; Character to C
E6C6 CDD9FC             CALL    CONMON          ; Send it
E6C9 C1                 POP     BC              ; Restore buffer length
E6CA F1                 POP     AF              ; Restore character
E6CB C9                 RET

E6CC CD05FD     CLOTST: CALL    GETINP          ; Get input character
E6CF E67F               AND     01111111B       ; Strip bit 7
E6D1 FE0F               CP      CTRLO           ; Is it control "O"?
E6D3 C0                 RET     NZ              ; No don't flip flag
E6D4 3A4510             LD      A,(CTLOFG)      ; Get flag
E6D7 2F                 CPL                     ; Flip it
E6D8 324510             LD      (CTLOFG),A      ; Put it back
E6DB AF                 XOR     A               ; Null character
E6DC C9                 RET

Dis-assembly of NASCOM ROM BASIC Ver 4.7                PAGE    26

E6DD CDA5E9     LIST:   CALL    ATOH            ; ASCII number to DE
E6E0 C0                 RET     NZ              ; Return if anything extra
E6E1 C1                 POP     BC              ; Rubbish - Not needed
E6E2 CD99E4             CALL    SRCHLN          ; Search for line number in DE
E6E5 C5                 PUSH    BC              ; Save address of line
E6E6 CD33E7             CALL    SETLIN          ; Set up lines counter
E6E9 E1         LISTLP: POP     HL              ; Restore address of line
E6EA 4E                 LD      C,(HL)          ; Get LSB of next line
E6EB 23                 INC     HL
E6EC 46                 LD      B,(HL)          ; Get MSB of next line
E6ED 23                 INC     HL
E6EE 78                 LD      A,B             ; BC = 0 (End of program)?
E6EF B1                 OR      C
E6F0 CAF8E3             JP      Z,PRNTOK        ; Yes - Go to command mode
E6F3 CD46E7             CALL    COUNT           ; Count lines
E6F6 CD61E8             CALL    TSTBRK          ; Test for break key
E6F9 C5                 PUSH    BC              ; Save address of next line
E6FA CD81EB             CALL    PRNTCR          ; Output CRLF
E6FD 5E                 LD      E,(HL)          ; Get LSB of line number
E6FE 23                 INC     HL
E6FF 56                 LD      D,(HL)          ; Get MSB of line number
E700 23                 INC     HL
E701 E5                 PUSH    HL              ; Save address of line start
E702 EB                 EX      DE,HL           ; Line number to HL
E703 CDADF9             CALL    PRNTHL          ; Output line number in decimal
E706 3E20               LD      A," "           ; Space after line number
E708 E1                 POP     HL              ; Restore start of line address
E709 CD9BE6     LSTLP2: CALL    OUTC            ; Output character in A
E70C 7E         LSTLP3: LD      A,(HL)          ; Get next byte in line
E70D B7                 OR      A               ; End of line?
E70E 23                 INC     HL              ; To next byte in line
E70F CAE9E6             JP      Z,LISTLP        ; Yes - get next line
E712 F209E7             JP      P,LSTLP2        ; No token - output it
E715 D67F               SUB     ZEND-1          ; Find and output word
E717 4F                 LD      C,A             ; Token offset+1 to C
E718 1143E1             LD      DE,WORDS        ; Reserved word list
E71B 1A         FNDTOK: LD      A,(DE)          ; Get character in list
E71C 13                 INC     DE              ; Move on to next
E71D B7                 OR      A               ; Is it start of word?
E71E F21BE7             JP      P,FNDTOK        ; No - Keep looking for word
E721 0D                 DEC     C               ; Count words
E722 C21BE7             JP      NZ,FNDTOK       ; Not there - keep looking
E725 E67F       OUTWRD: AND     01111111B       ; Strip bit 7
E727 CD9BE6             CALL    OUTC            ; Output first character
E72A 1A                 LD      A,(DE)          ; Get next character
E72B 13                 INC     DE              ; Move on to next
E72C B7                 OR      A               ; Is it end of word?
E72D F225E7             JP      P,OUTWRD        ; No - output the rest
E730 C30CE7             JP      LSTLP3          ; Next byte in line


This is an OCR’d version of the scanned page and likely contains recognition errors.











Page 32 of 67